U.S. Pat. No. 3,202,666, issued Aug. 24, 1965, discloses substituted 9H-pyrido (3,4-b) indole-1-carboxylic acid and derivatives thereof characterized by the formula: ##STR2## where R is hydrogen or a lower alkyl group of 1-4 carbon atoms. These compounds are said to have significant sedative and antiparasitic activity.
In U.S. Pat. No. 3,202,667, issued Aug. 24, 1965 compounds of the formula: ##STR3## where R is hydrogen or lower alkyl of 1-4 carbon atoms are disclosed as having utility as anti-inflammatory and sedative agents.
South African Pat. No. 65/5046 dated Sept. 16, 1965, discloses .beta.-carboline derivatives of the formula: ##STR4## where R.sub.1 can be hydrogen, R.sub.2 can be carboxy or alkoxycarbonyl, R.sub.3 can be hydrogen and R.sub.4 and R.sub.5 are hydrogen or alkyl radicals. The compounds disclosed in this patent are further defined in that the benzene ring A may be substituted by one or more alkoxy radicals. These compounds are disclosed as having utility as analgesic agents.